1. Technical Field
The present invention relates to the measurement of jitter and phase noise, and more particularly to a universal jitter meter and phase noise measurement for a second order phase-locked loop.
2. Description of the Related Art
Phase noise of a phase-locked loop (PLL) and a voltage-controlled oscillator (VCO) is measured using an on-chip spectrum analyzer, which involves the use of analog-to-digital converters (ADC), fast Fourier transforms (FFT) and discrete Fourier transforms (DFT). For very sensitive on-chip measurements, subsystems with a large dynamic range are needed. If the VCO and PLL run at a high frequency, direct observation of phase noise requires low noise mixers and long delay lines for higher sensitivity, which cannot be integrated on the chip. Conventional methods of measuring phase noise or jitter cannot be qualified as autonomous, as they require an external frequency reference with very low phase noise or an external spectrum analyzer.